wrMTrck doesn't detect worms

Good afternoon,

I am currently working with C. elegens and trying to determine the speed of my worms. Unfortunately the plug-in can’t recognize my worms or something like that, because it doesn’t give me any results. I hope someone in the forum can help me. I have attached a photo from a video recording.
I followed these instructions: http://www.phage.dk/plugins/download/wrMTrck.pdf



I believe @jsp will be the best person to advise you on this tool.